Composition for anionic lactam polymerization

ABSTRACT

A composition comprising a) at least one aliphatic or cycloaliphatic isocyanate compound having at least two isocyanate groups and b) at least one lactone, containing 4 to 7 carbon atoms and use of the composition as an activator for anionic lactam polymerization to obtain polyamides.

FIELD OF THE INVENTION

This invention relates to a composition for the preparation ofpolyamides by activated anionic polymerization of lactams.

BACKGROUND OF THE INVENTION

The activated anionic polymerization of lactams is used in numerousdifferent processes for the manufacture of polyimide shaped products.Unproblematic polymerization and the quality of the polyamides preparedby the various processes depend not only on the catalyst but to a largeextent also on the nature of the activator used.

Numerous compounds have been used as activators for the anionicpolymerization of lactams, i.e. acyl lactams (EP1449865), oxazolines(EP0786482), ethylenebisamides (US2010/0113661), isocyanates and thecorresponding masked isocyanate compounds.

Polyisocyanates or isocyanates, particularly diisocyanates, arefrequently used as activators. Hexamethylene diisocyanate is particularpreferred since it is a highly mobile liquid and as such affordsconsiderable advantage, particularly in continuous process in whichaccurate delivery by dosing pumps is important. One serious disadvantageof the use of hexamethylene diisocyanate, however is its toxicity whichis due to its high vapor pressure and which necessitates special safetymeasures.

In order to overcome this disadvantage blocked isocyanate compounds havebeen used. Caprolactam was used as one of such masking agents, forminghexamethylene biscarbamide caprolactam which has been classified asphysiologically harmless.

Other liquid activator systems for anionic lactam polymerization areknown in which isocyanate compounds are mixed with pyrrolidonecompounds, e.g. N-methyl pyrrolidone or N-ethyl pyrrolidone (EP0167907).One serious disadvantage of pyrrolidones, however, is their toxicity.According to EU regulation (EC) No 1272/2008 N-methylpyrrolidone hasbeen classified as being toxic for reproduction.

EP0697424 A1 discloses compositions comprising organic solvents andpolyisocyanates which may be emulgated in water. These compositions areintended for use in the preparation of aqueous dispersions which may inturn be employed as additives for adhesives, impregnating compositionsand coating compositions. In order to render the polyisocyanatessuitable for forming an emulsion in water, they have at least partiallybeen reacted with compounds providing hydrophilic moieties on thepolyisocyanate compounds.

WO 00/42091 discloses an antistatic molded resin article comprising apolyester amide resin prepared by copolymerizing a cyclic amide andspecific cyclic esters.

EP0134616 A1 and EP0135233 A1 disclose N-substituted carbamoyl-lactamcompounds which are described as suitable promoters or activators foranionic polymerization of lactams. These two prior art documentscorrespond to the basic concept identified above to use blockedisocyanate compounds.

U.S. Pat. No. 4,757,095 discloses lactones and lactams which may beutilized in the preparation of urethane modified pre-polymers which maybe employed for preparing micro cellular foams.

U.S. Pat. No. 5,684,119 discloses directly shapeable clear solutions ofpolyamide imides which may be employed for the preparation of yarns andfibers.

Additionally, in order to increase the impact strength of the obtainedpolyamides, impact modifiers, such as polyetheramines have to be addedto the anionic polymerization of lactams. However, conventional liquidactivator systems coagulate when supplied together with such impactmodifiers in the reaction container. To overcome this problem, separateaddition means are required, which complicates the polymerizationprocess. Sometimes the impact modifiers are mixed with thepolymerization catalyst before the addition to the lactam melt whichunavoidably leads to a decrease of the catalyst activity, sincepolymerization catalysts for anionic lactam polymerization are highlyhygroscopic.

An object of this invention is to provide a composition for anioniclactam polymerization which does not contain any pyrrolidone compounds,particularly no N-alkyl pyrrolidone compounds and which isstorage-stable and leads to polyamides of excellent quality.

DETAILED DESCRIPTION OF THE INVENTION

This object has been achieved with a composition comprising as componenta) at least one aliphatic or cycloaliphatic isocyanate compound havingat least two isocyanate groups and as component b) at least one lactone,containing 4 to 7 carbon atoms, and by the use of the composition foranionic lactam polymerization.

Suitable compounds for component a) are aliphatic or cycloaliphaticisocyanate compounds having at least two isocyanate groups. Diisocyanatecompounds are preferred, which may be selected from the group ofisophorone diisocyanate (IPDI), 4,4′-diisocyanato dicyclohexylmethane(H₁₂MDI), 1,6-hexamethylene diisocyanate (HDI), poly(isophoronediisocyanate), poly(4,4′-diisocyanato dicyclohexylmethane),poly(1,6-hexamethylene diisocyanate). The preferred diisocyanatecompounds are 1,6-hexamethylene diisocyanate (HDI) andpoly(1,6-hexamethylene diisocyanate), which may also be used incombination.

The compositions in accordance with the present invention do not containblocked isocyanates, and/or the compositions in accordance with thepresent invention do not contain polyisocyanates reacted with compoundsproviding hydrophilic groups as defined and disclosed in EP0697424 A1.

Suitable compounds for component b) are lactones containing 4 to 7carbon atoms preferably selected from the group of δ-valerolactone,γ-butyrolactone, ε-caprolactone. The preferred lactone isε-caprolactone.

The composition of the present invention may contain component a) in anamount of 60 to 80 weight %, preferably in an amount of 65 to 75 weight% and the most preferable amount is about 70 weight %.

The composition of the present invention may contain the component b) inan amount of 20 to 40 weight %, preferably in an amount of 25 to 35weight % and the most preferable amount is about 30 weight %.

In an another embodiment, which may be preferred in particular whenwishing to further tailor mechanical properties, it may be preferredwhen the amounts of components a) and b) in the composition inaccordance with the present invention are exactly inverse, i.e. when theamount of component a) is in the range of from 20 to 60 weight %,preferably 25 to 40 weight %, more preferably 25 to 35 weight % and mostpreferably about 30 weight %. Accordingly, the amount of the componentb) will be from 40 to 80 weight %, preferably from 60 to 75 weight %,more preferably from 65 to 75 weight % and most preferably about 70weight %.

These weight percentages are given relative to the total weight ofcomponent a) and component b).

As indicated above, component a) may comprise polymeric diisocyanates incombination with monomeric aliphatic or cycloalphatic isocyanatecompounds having at least two isocyanate groups. Of such monomericcompounds diisocyanates are preferred, which may be selected from thegroup of 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate(IPDI), 4,4′-diisocyanato dicyclohexylmethane (H₁₂MDI). The preferredmonomeric diisocyanate is 1,6-hexamethylene diisocyanate (HDI). Thismonomeric aliphatic or cycloalphatic isocyanate compound having at leasttwo isocyanate groups typically is employed in small amounts, i.e. it ispreferred when component a) comprises only polymeric isocyanates. Whenused together, the amount of monomeric isocyanate is typically below 2weight %, more preferably below 1 weight % based on the overallcomposition, such as in an amount of up to 0.4 weight %.

As indicated above, the composition in accordance with the presentinvention comprises components a) and b). In a preferred embodiment thecomposition in accordance with the present invention consists of thesetwo components, optionally only containing as a third component theconventional polyamide impact modifiers identified below. Preferably,other components are absent (with the only other exception beingoptional unavoidable impurities) and all compositions described hereinare intended for use as activator for anionic polymerization of lactams.Accordingly, the present invention provides compositions for use in theactivated anionic polymerization of lactams comprising or consisting ofthe components discussed herein, in the amounts disclosed.

The process for the production of the composition of the presentinvention is carried out by mixing the component a) and the component b)in suitable amounts. The process is carried out under substantiallywater-free conditions preferably under inert gas atmosphere. Thecomposition of the present invention is liquid at temperatures of around22° C. As a consequence, it can be stored in a separate, unheatedstorage vessel and metered to the lactam stream containing the catalystduring the casting step, resulting in polyamide formation.

Mechanical properties of the resulting polyamide obtained by the anioniclactam polymerization are substantially improved when using thecomposition of the present invention. During a cast polymerizationprocess of the lactam to polyamide, the lactone contained in thecomposition of the present invention is statistically inserted into thepolyamide chain and so generating defects in the macromolecular sectionof the polyamide preventing the entire crystallization of the castpolyamide. These macromolecular defects may be determined byDSC-analysis of the obtained polyamide. The obtained polyamide showssubstantially improved elastic modulus and impact strength.

It was surprisingly found that the obtained polyamides show improvedimpact strength when using the composition of the present invention as aliquid activator even without the addition of any impact modifiers,which simplifies the polymerization process.

In order further to increase the impact strength of the obtainedpolyamides, additional impact modifiers may however be added to theanionic polymerization of lactams in addition to the composition of thepresent invention.

Accordingly, it is further possible to add conventional polyamide impactmodifiers, such as those selected from the group of polyols, such aspolyetheramine (polyoxyalkylene triamine), commercially available underthe trade names Jeffamine® (Huntsman), Polyetheramin (BASF) or PC Amine®(Nitroil), Jeffamine® T-403, Jeffamine® T-3000, Jeffamine® T-5000,Polyetheramine T403, Polyetheramine T5000, PC Amine® TA 403, PC Amine®TA 5000 to the composition of the present invention.

Contrary to the problems described in connection with the prior artdisclosure (coagulation with conventional liquid activator compositions)no detrimental effect can be seen on the compositions in accordance withthe present invention, so that these impact modifiers surprisingly maybe employed together with the other essential components of theactivator compositions disclosed herein. While it is possible to obtainstorage stable compositions when mixing components a) and b) withpolyamide impact modifiers, it is nevertheless preferred to mix suchimpact modifiers with the activator system in accordance with thepresent invention only shortly before addition to the polymerizationsystem. Nevertheless, in view of the fact that these components may beadded to a polymerization system together without detrimental effect,the overall process is facilitated since no separate addition means isrequired for the impact modifier.

The impact modifiers may be used in an amount of up to 25 weight %(based on the total weight of the composition).

Preferably, the composition of the present invention comprises about 70weight % (such as 67-73, preferably 68-72 weight %) of component a),preferably poly(1,6-hexamethylene diisocyanate) and about 30 weight %(such as 27-33, preferably 28-32 weight %) of component b), preferablythe ε-caprolactone.

As indicated above, for certain applications, it may however also beadvantageous to inverse the amounts of components a) and b), i.e.preferred compositions in accordance with the present invention may alsocomprise about 30 weight % of component a) (such as 27-33, preferably28-32 weight %), particularly poly(1,6-hexamethylene diisocyanate) andabout 70 weight % (such as 67-73, preferably 68-72 weight %) ofcomponent b), in particular ε-caprolactone.

The process for the production of polyamide is carried out by theaddition of the composition of the present invention to lactam to bepolymerized. The composition of the present invention can be added tothe pure lactam or to pure lactam melt to be polymerized. Conventionalcatalysts are employed for polymerization, in accordance with theknowledge of the skilled person.

A suitable amount of the composition of the present invention to be usedin the anionic lactam polymerization process can be determinedappropriately depending on the physical properties required for thepolyamide. Suitable concentrations are 0.1 to 10 weight %, inembodiments 0.1 to 4, preferably 0.5 to 2.5 weight % based on 100 weight% of lactam to be polymerized.

The anionic lactam polymerization is carried out under substantiallywater-free conditions because water causes decomposition of the anionicpolymerization catalyst, leading to reduction in catalytic activity. Itis desirable that a contact of the polymerization system with oxygen isavoided as far as possible from the standpoint of prevention colorationof the resulting polyamide.

The anionic lactam polymerization is carried out in a reaction vesselequipped with a stirrer. In this case first ingredient mainly comprisingthe lactam and anionic polymerization catalyst for lactam and a secondingredient mainly comprising the composition of the present inventionand lactam are separately prepared. Prescribed amounts of these twoingredients are mixed and melted. The two ingredients are melted to atemperature to effect polymerization and combined at this temperature.

The reaction is performed at a temperature of from the melting point oflactam up to 200° C. at atmospheric pressure, under low pressure or invacuo. The polymerization reaction is completed within one hour.

Any catalyst known for anionic polymerization of lactams which may beused in the usual concentrations can be applied. Alkali metal lactamatesare preferred of which sodium lactamate is mostly preferred.

The addition of the composition of the present invention to the lactammelt which is to be polymerized is carried out either continuously ordiscontinuously. The composition according to the invention ispreferably suitable for the discontinuous polymerization of lactams toobtain polyamides, most preferable for discontinuous polymerization ofε-caprolactam to obtain polyamide, particularly PA-6.

The composition in accordance with the present invention in particularmay be used in polymerization reactions which are carried out forpreparing large sized polyamide moldings and/or hollow bodies andtypical fields of applications are in the field of rotomolding, or resintransfer molding processes which may in particular, be used in order toprepare moldings which comprise fiber reinforcements (employing moldswhich already comprise the fiber reinforcement) so that either thepolymerization is carried out in the presence of this fiberreinforcement or the polymerized melt is brought into contact with thereinforcement, so that the final polyamide impregnates and covers thefiber reinforcement.

The composition of the present invention is used as an activator foranionic lactam polymerization and is soluble in the lactam to bepolymerized. The composition of the present invention serves as anaccelerator for lactam polymerization and provides a comonomer componentto constitute a part of the resulting polyamide.

The composition according to the invention may be used for theproduction of shaped products and articles comprising said shapedproduct.

The present invention will now be explained in greater detail by way ofthe following Examples. In these Examples, the percents are by weightunless otherwise indicated.

EXAMPLES AND COMPARATIVE EXAMPLES Commercial Materials

BRUGGOLEN® C230 (L. Brüggemann): poly(1,6-hexamethylene diisocyanate)(polyHDI) (CAS 28182-81-2); N-methylpyrrolidone (NMP) (CAS 872-50-4);

BRUGGOLEN® C231 (L. Brüggemann): poly(1,6-hexamethylene diisocyanate)(polyHDI) (CAS 28182-81-2), N-ethyl pyrrolidone (NEP) (CAS 2687-91-4);

BRUGGOLEN® C20P (L. Brüggemann): blocked 1,6-hexamethylene diisocyanatein ε-caprolactam, 18-20% (CAS 5888-87-9);

BRUGGOLEN® C10 (L. Brüggemann): 17-19 weight % of sodiumε-caprolactamate in ε-caprolactam (CAS 2123-24-2, 105-60-2);

1,6-hexamethylene diisocyanate (CAS 822-06-0).

Analytical Methods Method Analysis BRGC 206

Method Analysis BRGC 206 is used to determine the reactivity ofcatalysts for the anionic polymerization of caprolactam in a short timetest.

Molten ε-caprolactam (technical, moisture <0.02%), catalyst (BRUGGOLEN®C10 (L. Brüggemann)) and activator polymerize giving polyamide. Duringthe process there are different stages of polymerization. Thesedifferences are classified visually.

Procedure

Weigh out each into two test glasses (A and B) 18.75 g caprolactam.

Close the test glasses with a plug of cork.

Place the test glasses in the oil bath to melt the caprolactam.

Add 1.5±1 g BRUGGOLEN® C10 to the melt caprolactam in test glass A.

Add 0.5-0.55 ml HDI to the molten caprolactam in test glass B by usingthe automatic burette and mix thoroughly with the glass rod.

1.050±0.001 g BRUGGOLEN® C20(P), C230, C231 or the composition of thepresent invention are weighed on the analytical balance and filled totest glass B.

After that homogenize with a glass stirrer.

At 130±1° C. (direct measurement of temperature in the test glass A)take the test glass A from the oil bath and add the contents of testglass B to test glass A. Close test glass A with the plug again, mix themolten material thoroughly by vigorous shaking and place it in the bath.At the same time start the stop-watch.

The stages of polymerization are analyzed visually. The time is measuredfor each of the three phases.

Classification

Phase 1 (T1), viscous; the molten mass does not move during lightrotation of the test glass; Phase 2 (T2), turbid; the clear melt startsto cloud; Phase 3 (T3), loosening of polymerized mass from the testglass wall; the melt starts to loosen itself from the wall in the upperregion of test glass.

The storage ability of the composition of the present invention isdemonstrated in Table 1 and has been evaluated in glass bottles in adesiccator at 22° C. (desiccant: orange gel) and in an oven at 40° C.Trace amounts of water in the composition have been determined by KarlFischer titration.

For the for the tensile strength tests presented in Table 2, test blocksof a size of 11 mm×170 mm were used. E-modulus-, σ_(M)-, ε_(M)-σ_(B)-,and ε_(B)-values have been evaluated using EN ISO 527 norm.

DSC-analysis (differential scanning calorimetry) has been carried outusing DIN EN 31357-1 norm.

Activator Compositions Example 1

The activator composition of the present invention is obtained by mixing70 weight % of poly(1,6-hexamethylene diisocyanate) (component a)) with30 weight % of ε-caprolactone (CAS 502-44-3) (component b)) at 22° C.

Comparative Examples 1 to 3 are commercially available activatorcompositions.

Comparative Example 1

BRUGGOLEN® C230 (L. Brüggemann): poly(1,6-hexamethylene diisocyanate)(Merck, CAS 28182-81-2) in N-methylpyrrolidone (NMP) (CAS 872-50-4),

Comparative Example 2

BRUGGOLEN® C231 (L. Brüggemann): poly(1,6-hexamethylene diisocyanate)(CAS 28182-81-2) in N-ethyl pyrrolidone (NEP) (CAS 2687-91-4)

Comparative Example 3

BRUGGOLEN® C20P (L. Brüggemann): blocked 1,6-hexamethylene diisocyanatein ε-caprolactam

The polymerization activity has been measured according to the test tubemethod

BRGC 206 outlined above (Table 1). Values T1 to T3 represent thestarting point of the polymerization (T1), crystallization of insolublepolymers (T2) and shrinking due to crystallization during thepolymerization (T3).

TABLE 1 Reactivity Stock Viscosity Water content T1 T2 T3 Compositionlocation [mPa · s] [w. %] [s] [s] [s] Example 1 desiccator 178.96 0.019945 71 162 Comparative desiccator 75.48 0.0113 48 72 152 Example 1Comparative desiccator 97.98 0.0163 43 73 154 Example 2 Example 1 oven178.96 0.0199 45 71 162 Comparative oven 75.48 0.0113 48 72 152 Example1 Comparative oven 97.98 0.0163 43 73 154 Example 2 8 weeks later:Example 1 desiccator 167.46 0.0177 35 53 110 Comparative desiccator71.48 0.0130 37 59 170 Example 1 Comparative desiccator 94.48 0.0156 3960 150 Example 2 Example 1 oven 169.46 0.0155 40 62 170 Comparative oven77.98 0.0198 39 61 152 Example 1 Comparative oven >500 0.0337 41 65 170Example 2

As can be taken from Table 1, viscosity of the activator composition ofthe present invention remains constant. Conventional activators show atelevated temperatures significantly increased viscosities as can be seenin Comparative Example 2. The activator composition of the presentinvention does not show any yellowing even at 40° C., whereas theactivator of the prior art shows yellowing at 40° C., which can bedetermined visually.

Further, the activator composition of the present invention does notcontain any toxic substances when compared to conventional activatorsystem of Comparative Example 1. Additionally, smell nuisance can bereduced when using the composition of the present invention, sincecaprolactone has a boiling point of 235° C. and conventional lactampolymerization is carried out at up to 200° C. (boiling point of NMP is203° C. and of NEP 212° C.).

Polyamides Obtained with the Activator Composition Example 2

In two glass round bottom flasks A and B 400 g of ε-caprolactam in eachare placed and melted in an oil bath at 150° C. (temperature of themolten ε-caprolactam is 100° C., measured in the flask). Then, bothflasks are flushed with nitrogen. 6.4 g of sodium caprolactamatecatalyst (BRUGGOLEN® 10) is added to the molten ε-caprolactam flask Aand stirred with a glass rod. After complete homogenization of mixtureB, 5.6 g of the composition of the present invention (Example 1) isadded to the flask B and heated to melt. After both melts (A and B) arehomogenized, melt B and melt A, having 135° C. are simultaneously filledin a casting mold which was flushed with nitrogen gas before fillingboth melts A and B into the mold. The polymerization reaction iscompleted within 30 minutes.

Comparative Example 4

In two glass round bottom flasks A and B 400 g of ε-caprolactam in eachare placed and melted in an oil bath at 150° C. (temperature of themolten ε-caprolactam is 100° C.). Then, both flasks are flushed withnitrogen. 6.4 g of sodium caprolactamate catalyst (BRUGGOLEN® 10) isthen added to the molten ε-caprolactam flask A. Subsequently, 1.8 mL of1,6-hexamethylene diisocyanate (HDI) are added to the flask B andstirred with a glass rod. After complete homogenization of this mixture,5.6 g of BRUGGOLEN® 230 is added to the flask B, heated to melt. Afterboth melts (A and B) are homogenized, melt B and melt A, having 135° C.are simultaneously filled in a casting mold which was flushed withnitrogen gas before filling both melts A and B into the mold. Thepolymerization reaction is completed within 30 minutes.

Comparative Examples 5 and 6 were similarly prepared as ComparativeExample 4, where BRUGGOLEN® 231 (Comparative Example 5) or BRUGGOLEN®20P (Comparative Example 6) were used as activators in same amountsinstead of BRUGGOLEN® 230 (Comparative Example 4).

TABLE 2 Tensile Strength E-Modulus σ_(M) ε_(M) σ_(B) ε_(B) Polyamide[MPa] [MPa] [%] [MPa] [%] Example 2 2280 61.7 24 55.1 32 ComparativeExample 4 2400 64.1 25 57.9 36 Comparative Example 5 1960 60.1 33 52.145 Comparative Example 6 3160 83.3 5.2 82.0 5.8

As can be seen from the Table 2, the obtained polyamide block when usingthe activator composition of the present invention shows improvedelongation at break values. L_(B) value of Example 2 is 32% versusε_(B)-value of Comparative Example 6 is 5.8%. The elastic modulus(E-Modulus) of the polyamide of the Example 2 is significantly lower(2280 MPa) than the elastic modulus of the polyamide of the ComparativeExamples 4 and 5.

Additional experiments in accordance with the previous description werecarried out using activator compositions consisting ofpoly(1,6-hexamethylene diisocyanate) and ε-caprolactone with the onlyexception that the ratio (by weight) of these components was changedfrom 70:30 (Example 1) to about 30:70, while at the same time increasingthe total amount of activator composition used so that the absoluteamount of component a) remains unchanged (based on the total weight ofthe polymerization composition). Making this modification in accordancewith the present invention resulted in polyamide compositions withhighly satisfactory mechanical properties and by further varying thetotal amount of component b) in the polymerization system (byappropriately readjusting the activator composition), it was possible totailor mechanical properties. With increasing amounts of component b),stiffness is reduced, while tensile strength is likewise reduced,whereas tensile elongation increases. Break stress is likewise reducedwith increasing content of component b) while elongation at break andimpact strength increase, as well as residual monomer content. Withdecreasing content of component a) stiffness increases, tensile strengthincreases, tensile elongation decreases, break stress increases,elongation at break decreases while residual monomer content in thefinal molding decreases while impact strength also decreases.

Overall, it is therefore readily apparent that the activator system andcomposition in accordance with the present invention provides a veryadvantageous option to tailor properties of the final polyamide moldingby increasing or decreasing the amounts of components a) and b),respectively, as well as their weight ratio. As outlined above, thecomposition in accordance with the present invention is highly stableand provides less environmental or safety or health concerns comparedwith prior art compositions, so that the possibility to tailorproperties of a polyamide molding during polymerization thereof isenabled without increasing health or environmental hazard.

Overall, the viscosity of the compositions of the present inventionremain constant at elevated temperatures. The compositions of thepresent invention do not show any yellowing even at 40° C., whereasactivator compositions of the prior art show yellowing at 40° C.Further, the compositions of the present invention do not contain anytoxic substances when compared to conventional activator systems.Additionally, smell nuisance can be reduced when using the compositionof the present invention.

1. A composition comprising: a) at least one aliphatic isocyanatecompound having at least two isocyanate groups; b) at least one lactone,containing 4 to 7 carbon atoms.
 2. The composition of claim 1 whereincomponent a) comprises poly(1,6-hexamthylene diisocyante).
 3. Thecomposition of claim 1 wherein component b) comprises ε-caprolactone. 4.The composition of claim 1 wherein component a) is present in an amountof 30 to 80 weight %.
 5. The composition of claim 1 wherein component a)is present in an amount of 60 to 80 weight %.
 6. The composition ofclaim 1 wherein component a) is present in an amount of 20 to 40 weight%.
 7. The composition of claim 1 wherein component b) is present in anamount of 20 to 80 weight %.
 8. The composition of claim 1 whereincomponent b) is present in an amount of 20 to 40 weight %.
 9. Thecomposition of claim 1 wherein component b) is present in an amount of60 to 80 weight %.
 10. A process for producing a composition of claim 1comprising the step of mixing component a) with component b).
 11. Aprocess for producing a polyamide, wherein the process comprises addinga suitable amount of a composition of claim 1 to a suitable amount of alactam.
 12. The process of claim 11 wherein the composition of claim 1is added in an amount of from 0.1 to 10 weight % based on 100 weight %of the lactam.
 13. The process of claim 12 wherein the composition ofclaim 1 is added in and amount of from 0.1 to 4 weight % based on 100weight % of the lactam.
 14. The polyamide obtained from the process ofclaim
 11. 15. A shaped product comprising the polyamide of claim
 14. 16.An article comprising the shaped product of claim
 15. 17. A method ofactivating an anionic polymerization of a lactam comprising adding asuitable amount of a composition of claim 1 to a suitable amount of thelactam and polymerizing the lactam in the presence of an anionicpolymerization catalyst.